Process forthe production of



Reissued Dec. 29, 1942 UNITED STATES PATENT OFFICE,

PROCESS FOR THE PRODUCTION OF ETHYLENE OXIDE Theodore Emile Lefort, Paris, France, assignor, by mesne assignments, to Carbide and Carbon Chemicals Corporation, New York, N. Y., a corporation of New York No Drawing. Original No. 1,998,878, dated April 23, 1935, Serial No. 600,578, March 22, 1932. Reissue No. 20,370, dated-May 18, 1937, Serial No. 102,613, September 25, 1936; This application for reissue September 18, 1942, Serial No. 458,887. In France March 27, 1931 3 Claims.

This reaction takes place at atmospheric pressure but, for commercially carrying the said process into practice, pressure can be employed, for instance a pressure of 50 kilograms per square ceistimeter, at a temperature between 150 and 40 C.

The following catalyzers may be used:

(1) Silver alone.

(2) Silver activated by introducing therein small proportions of gold, copper or iron.

(3) Silver alone, bismuth alone and antimony alone.

(4) The mixtures of antimony, bismuth, silver.

(5) The mixtures of bismuth and silver.

'And, generally speaking, the mixtures, in the same conditions, of these metals with their oxides and the mixtures of the oxides alone of these metals, in the same conditions.

The ethylene can be obtained from any source of supply: gas from coke ovens, hydrogenation of acetylene, dehydration of ethyl alcohol, and the like.

Water can be admitted in the reaction vessel, either in the liquid state, or as steam.

The oxygen can be the oxygen of the air, this latter gas being introduced in the reaction.

The efficiency of the reaction is increased by diminishing the CO2 which is formed, by introduction, in this reaction, of a suitable quantity of water. A suitable volume of CO2 can also be previously introduced in the reacting gases.

For increasing the yield in ethylene oxide, the process can also be carried out under a pressure lower than atmospheric pressure.

Experiments have shown that silver could be activated by introducing, in this body, small quantities either of gold, or of copper, or 01 iron.

Thus, a mixture containing silver, gold, copper and iron, gives very satisfactory results and allows a specific reaction; the only foreign product obtained in the reaction is CO2 which can be easily removed. Aldehydes formed exist only as traces.

Moreover, the applicant has found that the reaction giving CO: is, contrarily to previous belief, a reaction of oxidation independent from that giving ethylene oxide and from that giving aldehydes. From experiments effected by the applicant, it results that, if water is introduced in suitable quantity, the reaction is not only facilitated, as above stated, but, in addition, the reaction giving CO2, probably by direct oxidation of ethylene according to the equation:

is checked, owing, as is probable, to the partial pressure of water. From these experiments, it can be concluded that if a certain quantity of CO: is previously introduced, in addition, in the reacting gases, the partial pressure of CO: will produce its effect, and the reaction of oxidation of ethylene into C02 will be completely checked resulting in a considerable increase in the efilciency of the operation. Moreover, it is to be noted that, when the synthetic operation is efl'ected under partial vacuum, the yield in ethylene oxide is increased.

Several modi operandi for carrying the process into practice, will be indicated hereinafter, by way of example only.

Modus operandi I In a plant constructed for resisting to high pressures, ethylene on the one hand, and air on the other hand, are separately compressed by means of suitable compressors.

The mixture of air and ethylene can also be compressed by taking the necessary precautions in order to avoid the risk of explosion.

These two gases will be led, together with hydrogen or not, into a reaction tube resisting to the pressure of several hundreds of kilograms, containing one of the catalyzers indicated above, and heated, for instance, to a temperature of 200 C. This tube communicated moreover with a circulating pump allowing to introduce water under pressure.

The reaction will take place in this tube in which ethylene is simultaneously subjected to the action of molecular oxygen and water. By controlling the outputs, a continuous operation will be obtained. Ethylene oxide thus formed will be separated from the other gases, for instance, by condensation.

Modus operandi II Silver in powder form, or in the form of a wire gauze, and placed or not on a support or carrier, is introduced in a tube, made for instance of silica, and, after the said tube has been heated to a temperature comprised between 150 and 400 C., a mixture of ethylene, air, water vapour, and hydrogen is caused to pass therethrough. The proportion of hydrogen is about 5% of the total mixture. The ethylene oxide produced can be separated from the gases issuing from the tube.

Modus operandi III A silver colloid is introduced in a high pressure tube which has been filled with water. Pure ethylene under pressure is then added in order that it can dissolve in the water.

The tube is subsequently heated between 150 and 400 C., then air and hydrogen are slowly introduced. The introduction of air is stopped when the totality of ethylene is converted into ethylene oxide.

From ethylene oxide produced according to the processes which have been indicated above, it is possible to obtain, by simple saponiiication, ethylene-glycol, or by other known methods; any derivative of ethylene-glycol.

The reaction, for obtaining ethylene-glycol, can be written as follows:

lIzC-OII The experiments effected by the applicant have shown that, in presence of the catalyzers indicated, water, in the form of steam or not, considerably promotes the reaction ensuring the production of ethylene oxide..

What is claimed as the invention and is desired to secure by Letters Patent is:

i. A process for the production of ethylene oxide, consisting in subjecting ethylene to the simultaneous action of oxygen and water at a temperature between 150 and 400 C. in the presence of a catalyst composed of silver activated by small quantities oi ametal selected from agroupconsisting of gold, copper and iron.

2. A process for the production of ethylene oxide, consisting in subjecting ethylene to the simultaneous action of oxygen and water at a tem- V perature betwen 150 and 400 C. in the presence of a catalyst composed essentially of silver to form ethylene oxide substantially without aldehydes.

3. The process of making ethylene oxide by the direct chemical combination of oxygen with ethylene in the proportions of one atom of oxygen to one molecule of ethylene, which comprises introducing a mixture containing ethylene, molecular oxygen and water into a reaction vessel wherein the ethylene is subjected to the simultaneous action of the oxygen .and'the water; conducting said mixture through a reaction zone; controlling the temperature of said zone to maintain said mixture therein at a temperature between about and 400 C.; subjecting said mixture in said zone to intimate contact with an active surface catalyst material composed essentially of silver which favors the direct oxidation of said ethylene in said mixture by said molecular ozygen to form oxidation products containing ethylene oxide in the presence of water and which does not favor the existence in said products of substantial amounts of aldehydes; correlating the passage of said mixture through said reaction zone in the presence of said catalyst and the controlled elevated temperature of said mixture and said catalyst to efiect said oxidation of said ethylene directly to form substantial amounts of ethylene oxide; and thereafter recovering ethylene oxide-containing product.

THEODORE EMILE LEFORT. 

